Magneto-impedance effect in nanostructured soft ferromagnetic alloys

Abstract

Nanostructured Fe-based alloys have softer magnetic properties, such as larger saturation polarizations and magnetic permeabilities, smaller anisotropies and coercive fields and vanishing magnetostrictions, than their precursor alloys in the amorphous state. The softest magnetic properties are obtained for the smallest nanocrystalline grain sizes (between 10 and 20 nm), and these nanostructured materials are very suitable for use as high-frequency electronic components in magnetic devices or magnetic sensors based on the magnetoimpedance (MI) effect. In this work we study the correlation between the structural, electrical and magnetic properties together with the MI effect response in some heat-treated Finemet type and FeZrB ribbons. We show that the maximum MI ratio of around 130% and a sensitivity to the applied magnetic field of 0.07% (A m−1)−1 is obtained in the heat-treated samples that show an optimum nanocrystalline state and exhibit softer magnetic properties.